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Phospholipase A2 In Salivary Glands Isolated From Tobacco Hornworms, Manduca Sexta, Hasan Tunaz, David W. Stanley
Phospholipase A2 In Salivary Glands Isolated From Tobacco Hornworms, Manduca Sexta, Hasan Tunaz, David W. Stanley
Department of Entomology: Faculty Publications
We describe a phospholipase A2 (PLA2) associated with the salivary glands of tobacco hornworms, Manduca sexta. This enzyme is able to hydrolyze arachidonic acid from the sn-2 position of PLs. Addition of the calcium chelator, EGTA, or calcium, to the Tris reaction buffer impaired the PLA2 activity, from which we infer the enzyme requires very low concentrations of calcium or perhaps other ions for optimal activity. PLA2 activity was sensitive to protein concentration (highest activity at 25 μg protein per μl), reaction time (optimal at 30 min), buffer pH (optimal at pH 8–10), …
An Entomopathogenic Bacterium, Xenorhabdus Nematophila, Inhibits Hemocytic Phospholipase A2 (Pla2) In Tobacco Hornworms, Manduca Sexta, Youngjin Park, Yonggyun Kim, Hasan Tunaz, David W. Stanley
An Entomopathogenic Bacterium, Xenorhabdus Nematophila, Inhibits Hemocytic Phospholipase A2 (Pla2) In Tobacco Hornworms, Manduca Sexta, Youngjin Park, Yonggyun Kim, Hasan Tunaz, David W. Stanley
Department of Entomology: Faculty Publications
The entomopathogenic bacterium, Xenorhabdus nematophila, induces immunodepression in target insects and finally leads to lethal septicemia of the infected hosts. A hypothesis has been raised that the bacteria inhibit eicosanoid-biosynthesis pathway to interrupt immune signaling of the infected hosts. Here, we show direct evidence that X. nematophila inhibits the activity of phospholipase A2 (PLA2), the initial step in the eicosanoid-biosynthesis pathway. Inhibition of PLA2 was dependent on both incubation time with X. nematophila and the bacterial concentration in in vitro PLA2 preparations of Manduca sexta hemocytes. While living bacteria inhibited PLA2 activity, heat-killed X. nematophila rather increased PLA2 activity. X. …